Texture- the look and feel of the rock's texture Grains- particles of minerals or other rocks that make up a rock Igneous rock- forms from the cooling of magma or lava Sedimentary rock- forms from particles of other rocks or the remains of plants or animals when they are pressed and cemented Metamorphic rock- an existing rock is changed by heat, pressure, or chemical reactions
Outline
How Geologists Classify Rocks
rocks important for building
mountains, hills, valleys, beaches, ocean floor, all made of rock
geologists look at the rock's color/texture to find out its mineral composition
Texture
smooth, glassy, rough, or chalky
a rock's grains gives its texture
terms based on size, shape, pattern
Grain Size
large, easy to see (coarse grained)
small, seen through microscope (fine-grained)
Grain Shape
some looks like:
fine sand
small seeds
exploding stars
some are:
jagged
rough
fine
smooth
Grain Pattern
some lies in:
flat layers (__)
wavy, swirling patterns (~)
multicolored beads (.........)
No Visible Grain
not all rocks have grains
none because they cool very fast when they form
smooth, shiny, glassy
Mineral Composition
geologist can observe shape/size
must cut rock very thin to let light shine through crystals
test rock's surface with acid tells whether rock's minerals include compounds or carobnates
testing with magnet tells elements are iron or nickel
Origin
igneous rock
forms by the cooling of magma or lava
sedimentary rock
forms by the process of pressing and cementing sediments
Table of Contents
5.1 Classifying Rocks
Vocabulary
Texture- the look and feel of the rock's texture
Grains- particles of minerals or other rocks that make up a rock
Igneous rock- forms from the cooling of magma or lava
Sedimentary rock- forms from particles of other rocks or the remains of plants or animals when they are pressed and cemented
Metamorphic rock- an existing rock is changed by heat, pressure, or chemical reactions
Outline
How Geologists Classify Rocks
Texture
Mineral Composition
Origin